Biometrics is the statistical study of biological data. According to biometrics, every person has certain biological characteristics or traits that are virtually unique. In other words, biometric data can be used to identify an individual to a statistical certainty.
Biometric identification can be used for a variety of purposes, not the least of which is security. For instance, fingerprint scanners, retina scanners, DNA analyzers, facial recognition tools, and various other techniques and devices can collect biometric data and use the data to authenticate the identity of a would-be user. Biometric-based security measures can be used in place of, or in addition to, knowledge-based security measures, such as passwords or PINs (personal identification number) to access an ATM (automatic teller machine), a computer, a PDA (personal data assistant), a cell phone, or virtually any other device or service.